Cam assembly



Nov. 2, 1965 L. BONO 3,214 9 CAM ASSEMBLY Filed May 10, 1963 ZNVENTQR ym M TTORNEYS United States Patent 3,214,996 CAM ASSEMBLY Luigi Bono, Pavia, Italy, assignor to Necchi Societa per Azioni, Pavia, Italy Filed May 10, 1963, Ser. No. 279,436 Claims priority, application Italy, May 16, 1962, 9,695/ 62, Patent 674,964 7 Claims. (Cl. 74-568) This invention relates in general to new and useful improvements in sewing machines, and more particularly relates to means for rapidly locking on their support the interchangeable control cams of a sewing machine.

Modern sewing machines are provided with control cams to effect either the semi-automatic operation or the automatic operation thereof. A sewing machine is provided with a plurality of such control cams and the control cams are positioned in the sewing machine in accordance with the desired type and pattern of stitching to be accomplished.

This invention has as a primary object the provision of a support for control cams on which the control cams may be readily positioned and from which the control cams may be readily removed whereby the replacement of control cams may be readily accomplished.

Another object of this invention is to provide a novel support for the feeding control cams of a sewing machine, the support being provided with a retaining ring which, in one position, prevents the ready replacement of control cams, and in a second position securely holds the control cams in place.

In order to provide for the desired interchangeability of control cams of a sewing machine, th support is provided with an axial key adapted to engage a keyway of the interchangeable cams and carries a retaining ring having a similar key portion, the retaining ring being freely rotatable on the support in such a manner that when the key and key portion are aligned, the application or removal of the control cams is possible while otherwise the control cams are locked between the key portion of the retaining ring and a shoulder on the support.

With the above and other objects in View that will hereinafter appear, the nature of the invention will be more clearly understood by a reference to the following detailed description, the appended claims and the several views illustrated in the accompanying drawings.

In the drawings:

FIGURE 1 is a perspective View of the control cam support and shows generally the details thereof in a position for the reception of cams.

FIGURE 2 is a perspective view similar to FIGURE 1 and shows the support with control cams positioned thereon and locked in place, portions of the control cams being broken away and shown in section in order to clearly illustrate the relationship of the control cams to the support.

FIGURE 3 is an exploded perspective View of the support in its disassembled condition and shows associated therewith a drive shaft for the support and the control cams to be positioned on the support.

Referring now to the drawings in detail, it will be seen that the support for the interchangeable cams is formed of a bushing, generally referred to by the numeral 1. The bushing 1 has an axial hole extending up through the lower portion thereof and terminating at the top of the bushing in a rectangular slot 2. The bushing 1 is received over an end of a drive shaft 3 which terminates at its upper end in a key 4. The key 4 is received within the rectangular slot 2 to drivingly connect the bushing 1 to the shaft 3.

The bushing 1 is provided at its lower end with a shoulder 5 and above the shoulder 5, the bushing has a cylindrical surface 6. A pair of axially extending keys 7 and 3,214,996 Patented Nov.-2, 1965 8 project from the surface 6 in diametrically opposite relations.

The cylindrical surface 6 terminates short of the upper end of the bushing 1 and the upper portion of the bushing 1 includes a cylindrical surface 9 of a reduced cross section as compared to the cylindrical section 6. A retaining ring 10 is mounted on the cylindrical surface 9 and is freely rotatable with respect to the bushing 1. The retaining ring 10 has an outer cylindrical surface which is of the same diameter as the cylindrical surface 6 and which is aligned with the cylindrical surface 6 when the retaining ring 10 is mounted on the bushing 1.

The retaining ring 10 is retained on the bushing 1 by means of a resilient retainer 11. The retainer 11 is formed of a resilient wire and includes a generally C- shaped central portion 20 and a pair of outer arcuate wings 21 'which are axially displaced from the C- shaped portion 20. The extreme upper part of the bushing 1 is provided with a circumferential groove 12 in which the C-shaped portion 20 of the retainer 11 is received. The upper end of the retaining ring 10 is recessed, as at 22, to receive the wings 21 of the retainer 11. It will be readily apparent that the retainer 11 elastically opposes axial displacement of the retaining ring along the bushing 1.

The retaining ring 10 carries a pair of key portions 13 and 14 which are in diametrical opposite relation and which project from the outer surface of the retaining ring 10. The key portions 13 and 14 correspond generally to the keys 7 and 8 and terminate at their lower ends in projecting detents 15. The upper ends of the keys 7 and 8 are of a cross section complementary to the detents 15 to define sockets 16 in which the detents 15 may seat.

A plurality of interchangeable cams 17 are shown in FIGURES 2 and 3. Each of the cams 17 is of a conventional construction and has a central opening therethrough for receiving the bushing 1. In addition, each of the earns 17 is provided with a pair of diametrically opposite keyways 18 for engagement over the keys 7 and 8. Also, each cam 17 is provided with a central portion 19 of a slightly greater thickness.

Referring now to FIGURE 1 in particular, it will be seen that when the retaining ring 10 is recessed at an end so that the key portions 13 and 14 thereof are aligned with the keys 7 and 8, the key portions 13 and 14 are interlocked with the keys 7 and 8 so as to retain the retaining ring 10 in this position. At this time the key portions 13 and 14 form extensions of the keys 7 and 8, respectively. When the retaining ring 10 is retained in this position, it is possible to freely position earns 17 on the bushing 1 or to remove the cams therefrom. The particular bushing illustrated in the drawings is adapted to receive three cams 17, although the length of the bushing 1 may be varied to accommodate any desired number of cams in accordance with the requirements of the sewing machine. After the required number of cams have been applied to the bushing 1, the retaining ring 10 is rotated to a position wherein the key portions 13 and 14 ar out of alignment with the keys 7 and 8, as is shown in FIGURE 2. The detents 15 of the key portions 13 and 14 now rest upon the uppermost cam 17 and serve to resiliently urge the earns 17 towards the shoulder 5 whereby the cams 17 are securely locked on the bushing 1 for rotation therewith.

It is to be understood that the sewing machine, of which other portions thereof have not been illustrated, will be provided with suitable feelers or followers for engaging the cams 17 to control the operation of the sewing machine. This is conventional and not shown in the drawing. Also, it is to be understood that the drive shaft 3 is a conventional part of a sewing machine and may be driven in any manner, including through a clutch which has not been shown.

Although only a preferred embodiment of the invention has been specifically illustrated and described herein, it is to be understood that minor variations may be made in the construction of the support within the spirit and scope of the invention, as defined in the appended claims.

' 1. A cam holder for cams having keyways therein, said cam holder comprising a bushing having a drive shaft receiving bore and a cam retaining shoulder adjacent one end, an axial key on the outer surface of said bushing for interlocking engagement with cams, and a reduced cylindrical portion remote from said shoulder, and a retaining ring rotatably journalled on said cylindrical portion, said retaining ring having an outer diameter equal to the outer diameter of said bushing for the passage of cams thereover and a key portion for locking cams on said bushing.

2. The cam holder of claim 1 wherein said retaining ring is held on said bushing by a resilient retainer carried on the upper end of said bushing and which resiliently biases said retaining ring against said bushing whereby said key portion is normally retained in a cam clamping position.

3. The cam holder of claim 1 wherein said retaining ring is held on said bushing by a resilient retainer carried on the upper end of said bushing and which resiliently biases said retaining ring against said bushing whereby said key portion is normally retained in a cam clamping position, and said bushing key has a socket on its end complementary to a detent of the lower end of said portion whereby when said key portion is aligned with said key, said key portion is urged into interlocked engagement with said key to maintain said alignment during the placement and removal of cams.

4. The cam holder of claim 1 wherein said retaining ring is held on said bushing by a resilient retainer carried on the upper end of said bushing and which resiliently biases said retaining ring against said bushing whereby said key portion is normally retained in a cam clamping position, said retainer being in the form of a resilient wire having a C-shaped central portion and outer axially offset wings, said bushing having an annular groove receiving said C-shaped central portion, and said wings bearing against said retaining ring.

5. The cam holder of claim 1 wherein said retaining ring is held on said bushing by a resilient retainer carried on the upper end of said bushing and which resiliently biases said retaining ring against said bushing whereby said key portion is normally retained in a cam clamping position, said retaining ring having a recessed upper end receiving said resilient retainer.

6. The cam holder of claim 1 wherein said retaining ring is held on said bushing by a resilient retainer carried on the upper end of said bushing and which resiliently biases said retaining ring against said bushing whereby said key portion is normally retained in a cam clamping position, said retainer being in the form of a resilient wire having a C-shaped central portion and outer axially offset wings, said bushing having an annular groove receiving said C-shaped central portion, and said wings bearing against said retaining ring, said retaining ring having a recessed upper end receiving said resilient retainer.

7. A replaceable cam assembly for a sewing machine comprising a bushing having a drive shaft receiving bore and a cam retaining shoulder at one end, an axial external key on said bushing, a plurality of interchangeable cams telescoped over said bushing and having keyways receiving said key, said cams being seated on said shoulder, said bushing having a reduced cylindrical portion adjacent said cams remote from said shoulder, a retaining ring rotatably journalled on said cylindrical portion, said retaining ring having an outer diameter equal to the outer diameter of the bushing for the passage of cams thereover and having a key portion alignable with said bushing key and normally being misaligned and bearing against said cams, and a resilient retainer carried on the upper end of said bushing and which resiliently biases said retaining ring against said bushing, holding said retaining ring on said bushing with said key portion in pressure contact with an adjacent one of said cams.

References Cited by the Examiner UNITED STATES PATENTS 2,999,471 9/61 Benink et al 74-568 X BROUGHTON G. DURHAM, Primary Examiner.

MILTON KAUFMAN, Examiner. 

7. A REPLACEABLE CAM ASSEMBLY FOR A SEWING MACHINE COMPRISING A BUSHING HAVING A DRIVE SHAFT RECEIVING BORE AND A CAM RETAINING SHOULDER AT ONE END, AN AXIAL EXTERNAL KEY ON SAID BUSHING, A PLURALITY OF INTERCHANGEABLE CAMS TELESCOPED OVER SAID BUSHING AND HAVING KEYWARS RECEIVING SAID KEY, SAID CAMS BEING SEATED ON SAID SHOULDER, SAID BUSHING HAVING A REDUCED CYLINDRICAL PORTION ADJACENT SAID CAMS REMOTE FROM SAID SHOULDER, A RETAINING RING ROTATABLY JOURNALLED ON SAID CYLINDRICAL PORTION, SAID RETAINING RING HAVING AN OUTER DIAMETER EQUAL TO THE OUTER DIAMETER OF THE BUSHING FOR THE PASSAGE OF CAMS THEREOVER AND HAVING A KEY PORTION ALIGNABLE WITH SAID BUSHING KEY AND NORMALLY BEING MISALIGNED AND BEARING AGAINST SAID CAMS, AND A RESILIENT RETAINER CARRIED ON THE UPPER END OF SAID BUSHING AND WHICH RESILIENTLY BIASES SAID RETAINING RING AGAINST SAID BUSHING, HOLDING SAID RETAINING RING ON SAID BUSHING WITH SAID KEY PORTION IN PRESSURE CONTACT WITH AN ADJACENT ONE OF SAID CAMS. 